[client] Name the force-reset test for the behavior it proves

The silence after ResetMode follows from the undecided mode alone, and the
closing SetVersion overwrites forceUpdate from its argument, so the test
cannot observe whether the flag itself was cleared. Name it for the stale
directive staying silent, which is what it asserts.

client/internal/updater/manager_mode_test.go

@@ -116,7 +116,7 @@ func Test_SetDownloadOnly_ClearsPendingVersion(t *testing.T) {
 	}
 }
 
-func Test_ResetMode_DropsForceUpdate(t *testing.T) {
+func Test_ResetMode_SilencesStaleForceDirective(t *testing.T) {
 	tmpFile := path.Join(t.TempDir(), "update-test-force-reset.json")
 	recorder := peer.NewRecorder("")
 	sub := recorder.SubscribeToEvents()